Electrostatic discharge will ignite finely dispersed tantalum powder. To improve safety when working with tantalum powder, the user therefore should seek to reduce the risk of electrostatic sparking. One common generator of high electrostatic potential is plain plastic. For example, using ungrounded sections of plastic hose in a dust collection system can generate enough electrostatic charge and subsequent sparking to ignite the tantalum powder contained therein, potentially resulting in a dangerous explosion. Likewise, use of packaging materials that do not produce electrostatic charge will improve the safety of handling high-surface area tantalum powder.
Reference is made in the literature to extraction of oxygen from the dielectric oxide by the tantalum substrate at temperatures in excess of 200.degree. C. Smyth, D. M., Shirn, G. A., and Tripp, T. B., "Heat Treatment of Anodic Oxide Films on Tantalum", 110:12 J. Electrochem. Soc'y (1963). However, Applicant is unaware of any reference suggesting that significant reductions in oxygen pick-up during powder storage may be achieved by packaging under vacuum and/or argon blanket conditions, as presently claimed.
Accordingly, it is an object of the invention to provide packaging conditions that reduce the quantity of oxygen that passes through the oxide film.
It is a further object of the invention to improve the performance of capacitor-grade tantalum powder by reducing the quantity of oxygen dissolved in the substrate.
It is another object of the invention to improve the safety of storing and handling capacitor-grade tantalum powder by reducing the electrostatic charge allowed to build-up.
It is a still further object of the invention to provide superior capacitors made from tantalum powder packaged and stored under vacuum and/or argon blanket conditions.